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Work Tests to Evaluate Cardiorespiratory Fitness

Work Tests to Evaluate Cardiorespiratory Fitness

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Work Tests to Evaluate Cardiorespiratory Fitness

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  1. Work Tests to Evaluate Cardiorespiratory Fitness

  2. Objectives • Identify the sequence of steps in the procedures for evaluating cardiorespiratory fitness (CRF). • Describe one maximal and one submaximal field test used to evaluate CRF. • Explain the rationale underlying the use of distance runs as estimates of CRF. • Identify the common measures taken during a graded exercise test (GXT). • Describe changes in the ECG that may take place during a GXT in subjects with ischemic heart disease.

  3. Objectives • List three criteria for having achieved VO2 max. • Estimate VO2 max from the last stage of a GXT and list the concerns about the protocol that may affect that estimate. • Estimate VO2 max by extrapolating the HR/VO2 relationship to the person’s age-adjusted maximal HR. • Describe the problems with the assumptions made in the extrapolation procedure used in objective 8, and name the environmental and subject variables that must be controlled to improve such estimates.

  4. Objectives • Identify criteria used to terminate the GXT. • Explain why there are so many different GXT protocols and why the rate of progression through the test is of concern. • Describe the YMCA’s procedure to set the rate of progression on a cycle ergometer test. • Estimate VO2 max with the Åstrand and Ryhming nomogram given a data set for the cycle ergometer or step.

  5. Testing Procedures Screening Resting and Exercise Measures Field Tests for Measuring CRF Maximal Run Tests Walk Tests Canadian Home Fitness Test Outline • VO2 max Estimation of VO2 max from Last Work Rate Estimation of VO2 max from Submaximal Heart Rate Response • Graded Exercise Test: Protocols Treadmill Cycle Ergometer Step Test • Graded Exercise Tests: Measurements Heart Rate Blood Pressure ECG Rating of Perceived Exertion Termination Criteria

  6. Testing Procedures Screening • Signing consent form • Physical Activity Readiness Questionnaire (PAR-Q) • PARmed–X • Highlights absolute and relative contraindications for exercise • ACSM Risk Stratification • Low risk • Men <45 yr, women <55 yr, asymptomatic, ≤1 risk factor • Moderate risk • Men ≥45, women ≥55, or ≥2 risk factors • High risk • ≥1 sign or symptom or known disease

  7. Testing Procedures Decision Tree in the Evaluation of Cardiorespiratory Fitness Figure 15.1

  8. Testing Procedures PAR-Q Figure 15.2

  9. Testing Procedures Resting and Exercise Measures • Resting measures • Heart rate and blood pressure • Cholesterol • ECG • Exercise measures (GXT or field test) • Heart rate • Blood pressure • ECG • Symptoms • Angina pectoris • Dyspnea

  10. Testing Procedures In Summary • The steps to follow before conducting an exercise test to evaluate CRF include: a. signing of a consent form, b. screening, c. obtaining resting HR and BP as well as cholesterol and ECG measures.

  11. Field Tests for Estimating CRF Field Tests for Estimating Cardiorespiratory Fitness • Use natural activities • Walking, running, or stepping • Can test large numbers of people at low cost • Physiological responses may be difficult to measure • Motivation plays an important role in test results

  12. Field Tests for Estimating CRF Maximal Run Tests • Measure how far a person can run in a set time or how fast they can run a set distance • Cooper’s 12-minute run and 1.5-mile run • For adults • AAPHERD’s 1-mile run/walk and PACER test • For children • VO2 max estimates based on the linear relationship between running speed and oxygen cost of running • Duration of 10–20 minutes • Running at speed demanding 90–95% VO2 max • Minimize contribution of anaerobic energy sources

  13. Field Tests for Estimating CRF Estimating VO2 From Walk/Run Tests • Calculating VO2 from running speed • Calculating VO2 from walking speed VO2 = 0.2 ml•kg–1•min–1 per m•min–1 + 3.5 ml•kg–1•min–1 VO2 = 0.1 ml•kg–1•min–1 per m•min–1 + 3.5 ml•kg–1•min–1

  14. Field Tests for Estimating CRF A Closer Look 15.1Progressive Aerobic Cardiovascular Endurance Run (PACER) • Used in school children • Part of FITNESSGRAM testing battery • 20-meter shuttle run • Initial speed is 5.3 mph • Increases 0.3 mph with each level • Test terminated when student cannot keep up • Number of laps used to determine aerobic fitness • Reliability has been questioned • Compromises ability to detect changes in VO2 max

  15. Field Tests for Estimating CRF Aerobic Fitness Classifications

  16. Field Tests for Estimating CRF A Closer Look 15.2Cardiovascular Fitness Standards for Children • Normative standards • Percentile scores (75th percentile) • Criterion-reference standards • Describe the minimum level of fitness consistent with good health • Example: • VO2 max standards set at 42 ml•kg–1•min–1 for boys (5–17 y) • Tests designed to translate criterion values into performance outcomes • One-mile run times consistent with VO2 max values

  17. Field Tests for Estimating CRF Walk Tests • One-mile walk test requires simple measurements • VO2 max is based on: • Age (years), weight (pounds), sex (0 for female, 1 for male), time (min), and HR (beats/min) • As fitness improves, HR and/or time will be lower • Results in higher estimated VO2 max VO2 (ml•kg–1•min–1) = 132.853 – 0.0769 (wt) – 0.3877 (age) + 6.315 (sex) – 3.2649 (time) – 0.1565 (HR)

  18. Field Tests for Estimating CRF Canadian Home Fitness Test • Uses 8-inch steps to evaluate cardiorespiratory fitness • Measure HR after 3 minutes of stepping • Stop if it exceeds maximum allowable HR based on age • Continue for another 3 minutes if it is below maximum allowable HR • Fitness level is based on post-exercise HR

  19. Field Tests for Estimating CRF Fitness Evaluation from the Canadian Home Fitness Test

  20. Field Tests for Estimating CRF In Summary • Field tests for CRF use natural activities such as walking, running, and stepping in which large numbers of people can be tested at low cost. However, for some, physiological responses are difficult to measure, and motivation plays an important role in the outcome. • VO2 max estimates from all-out run tests are based on the linear relationship between running speed and the oxygen cost of running. • The Canadian Home Fitness Test is a step test that uses conventional 8-inch steps to evaluate cardiorespiratory fitness.

  21. Graded Exercise Tests: Measurements Graded Exercise Tests • Cardiorespiratory fitness measured using: • Treadmill • Cycle ergometer • Stepping bench • Incremental tests • Work rate increases every 2–3 minutes • until predetermined endpoint is reached • Tests can be maximal or submaximal

  22. Graded Exercise Tests: Measurements Heart Rate • Measured by • Palpation • Carotid or radial artery • Stethoscope • On chest wall • ECG • Heart rate displayed on monitor • Measured during exercise or in recovery • Recovery HR should be measured within first 15 seconds

  23. Graded Exercise Tests: Measurements Blood Pressure • By auscultation • During walking or cycling exercise • Subject should not be holding handlebar • Systolic BP • First Korotkoff sound • Diastolic BP • Fourth Korotkoff sound • Change in tone or muffling

  24. Graded Exercise Tests: Measurements ECG • Double product • Product of HR and systolic BP • Estimate of myocardial O2 demand • Arrhythmias • Irregularities in normal electrical rhythm • Atrial fibrillation • Premature junctional and ventricular contractions • Conduction disturbances • Depolarization is slowed or blocked • First-degree AV block or bundle branch block • Myocardial ischemia • Inadequate perfusion of myocardium • Angina pectoris • Symptom of ischemia • ST segment depression • Sign of ischemia

  25. Graded Exercise Tests: Measurements Three Types of ST Segment Depression Figure 15.3

  26. Graded Exercise Tests: Measurements Rating of Perceived Exertion (RPE) • Original 6–20 scale and revised scale (0–10) • Indicator of subjective effort • Way to track progress through a GXT • Can be used to prescribe exercise • Instructions “During the exercise test we want you to pay close attention to how hard you feel the exercise work rate is. This feeling should reflect your total amount of exertion and fatigue, combining all sensations and feelings of physical stress, effort, and fatigue. Don’t concern yourself with any one factor such as leg pain, shortness of breath, or exercise intensity, but try to concentrate on your total, inner feeling of exertion. Try not to underestimate or overestimate your feeling of exertion; be as accurate as you can.”

  27. Graded Exercise Tests: Measurements Original and Revised RPE Scales

  28. Graded Exercise Tests: Measurements Termination Criteria • Include signs and symptoms • Depend on: • Population being tested • Purpose of the test • ACSM’s Guidelines for Exercise Testing and Prescription • Appropriate for nondiagnostic GXTs

  29. Graded Exercise Tests: Measurements GXT Termination Criteria

  30. Graded Exercise Tests: Measurements In Summary • Typical measurements obtained during a graded exercise test include heart rate, blood pressure, ECG, and rating of perceived exertion. • Specific signs (e.g., fall in systolic pressure with an increase in work rate) and symptoms (e.g., dizziness) are used to stop GXT.

  31. VO2 Max VO2 Max • The gold standard measure of cardiorespiratory fitness • Very reproducible on same work instrument • Depends on work instrument • Highest on treadmill • Walking ~6% lower than running • Lower (~5–11%) on cycle ergometer • Arm ergometer values 70% of leg ergometer • VO2 max vs. VO2 peak

  32. VO2 Max Criteria for Achieving VO2 Max • Leveling off of VO2 with higher work rate <150 ml•min–1 or <2.1 ml•kg–1•min–1 • Post-exercise blood lactate >8 mmoles•L–1 • R >1.15 • HR within 10 beats•min–1 or age-predicted maximal HR • Usefulness has been questioned • Should not expect subjects to meet all criteria

  33. VO2 Max A Closer Look 15.3VO2 Max and the Plateau—Needed or Not? • Not all subjects achieve a plateau in VO2 • Led to development of secondary criteria • Several studies have demonstrated that a plateau is not needed for a “true” VO2 max • Highest VO2 measured during incremental exercise test not different from VO2 during subsequent test at higher work rate

  34. VO2 Max Estimation of VO2 Max From Last Work Rate • Direct measurement of VO2 max is often not practical • Complex and costly procedures • Can use equations to calculate estimated VO2 max from last stage of GXT • Must allow time for subject to reach steady state in each stage

  35. VO2 Max A Closer Look 15.4Error in Estimating VO2 max • Equations developed by actually measuring VO2 max in large numbers of subjects • Standard error (SE) • How far off the predicted VO2 max is from actual value • 1 SE describes 68% of estimates • VO2 max estimated from last stage of maximal test • SE = 3 ml•kg–1•min–1 • VO2 max estimated from HR in submaximal test • SE = 4–5 ml•kg–1•min–1 • VO2 max estimated from one-mile walk or 12-minute run • SE = 5 ml•kg–1•min–1

  36. VO2 Max Estimation of VO2 Max From Submaximal Heart Rate Response • Measure HR at several submaximal work rates • Up to 70–85% predicted maximal HR • Extrapolate submaximal HR to estimate VO2 max • A line is drawn through the HR points measured during the test and extrapolated to the age-adjusted estimate of maximal HR • Another line is dropped down from that point to the x-axis, and the VO2 max is identified • Problems • SD of Age-predicted maximal HR is ±11 beats•min–1 • Can result in over- or underestimation of VO2 max • Other factors affect submaximal HR response • e.g., dehydration, temperature, medications

  37. VO2 Max Estimation of VO2 max From Submaximal Cycle Ergometer Test Figure 15.4

  38. VO2 Max In Summary • The measurement of VO2 max is the gold standard measure of cardiorespiratory fitness. • VO2 max can be estimated based on the final work rate achieved in a graded exercise test. • VO2 max can be estimated from heart rate responses to submaximal exercise by extrapolating the relationship to the subject’s age-adjusted estimate of maximal heart rate. Careful attention to environmental factors that can affect the heart rate response to submaximal exercise is an important aspect of the procedures for these tests.

  39. Graded Exercise Test: Protocols Graded Exercise Test: Protocols • Consideration of the population tested • Submaximal vs. maximal test • Starting work rate • Rate of change of work rate • Mode of exercise • Treadmill • Cycle ergometer • Step test • Subjects must follow instructions carefully • Environmental conditions must be controlled • Temperature and humidity

  40. Graded Exercise Test: Protocols Treadmill • Use natural activities • Walking and running • Can accommodate a wide range of subjects • Least fit to most fit • Involve increasing speed and/or grade • Estimating VO2 max • Usually based on extrapolating submaximal HR • Test terminated at 85% age-predicted maximal HR • Could also be a single-stage test

  41. Graded Exercise Test: Protocols Treadmill GXT Protocols

  42. Graded Exercise Test: Protocols Estimation of VO2 Max from Submaximal Treadmill Test Figure 15.5

  43. Graded Exercise Test: Protocols Cycle Ergometer • Body weight is supported • Can accommodate subjects with orthopedic limitations • Work rate depends on resistance and pedal rate • Generally, pedal rate is maintained and resistance is increased • Estimating VO2 max • Based on extrapolating submaximal HR during incremental test • YMCA protocol • From a single-stage, 6-minute test • Åstrand and Ryhming nomogram

  44. Graded Exercise Test: Protocols YMCA Protocol Figure 15.6

  45. Graded Exercise Test: Protocols Example of the YMCA Protocol Used to Estimate VO2 max Figure 15.7

  46. Graded Exercise Test: Protocols Nomogram for Estimation of VO2 max from Submaximal HR Figure 15.8

  47. Graded Exercise Test: Protocols Step Test • Simple, inexpensive equipment • Protocols differ in: • Step height • Step rate • Estimating VO2 max • Based on extrapolating submaximal HR • Can also use Åstrand and Ryhming nomogram

  48. Graded Exercise Test: Protocols Predicting VO2 Max from Submaximal Step Test Figure 15.9

  49. Graded Exercise Test: Protocols In Summary • VO2 max can be estimated with the extrapolation procedure using the treadmill, cycle ergometer, or step. • The subject must follow directions carefully and environmental conditions must be controlled if the estimate of VO2 max is to be reasonable and reproducible.

  50. Study Questions • What is the sequence of steps used in evaluating cardiorespiratory fitness? • What is a health or cardiac risk inventory? Name one currently in use and explain its purpose. • A forty-year-old man runs 1.5 miles (2.415 m) in ten minutes. What is his estimated VO2 max? Is his value “normal”? • Draw an example of ST segment depression and describe its significance in the diagnosis of heart disease. • You are monitoring a GXT in which VO2 max is measured. How would you know if a person achieved VO2 max?